The next step is maxillofacial imaging from the metal-artifact-reduced CBCT image obtained in the previous stage. A final 3D maxillofacial image is obtained by weighted thresholding, which can further reduce the remaining streaking artifacts around teeth. The weighting region is determined depending on the geometry of the intra-oral scan data \(\mbox{\textbf {O}}\) . To extract the geometry, the \(\alpha \) -shape technique [1]} is used. It provides a family of piece-wise linear lines associated with the shape of the teeth. Fig. REF  shows the overall process.
